The long-term goal of this project is an understanding, at the molecular level, of the process of neurosecretion, which is responsible for the release of rapidly-acting neurotransmitters and longer-acting neuromodulators and trophic agents; these in turn are responsible for the modulation of synaptic activity, synaptic formation and maintenance, and synaptic plasticity in the nervous system. In searching for new components of this synaptic machinery, the applicants have identified a novel 27 kD vesicle-specific integral membrane protein in both large dense-core and small clear regulated secretory vesicles. The presence of this protein called synvesiclin in both types of secretory vesicles suggests that it plays an important role in secretory vesicle function. The specific goals of this proposal are designed to extend the characterization of synvesiclin and understand both its structure and its functional role in synaptic vesicle dynamics. Synvesiclin will be cloned and sequenced to obtain the primary structure of the protein. Additional antibodies will be generated to peptide epitopes of synvesiclin and used to test predictions about synvesiclin's orientation and post-translational modification. Predictions about the structural and functional features of synvesiclin will be tested by biochemical and genetic analysis. Antibodies will also be employed to examine regional expression of synvesiclin. The results of this work will lead to a better understanding of the fundamental processes responsible for neurosecretion.